The invention concerns a method for the transmission and reception of local radio programs in a common-wave broadcasting network, wherein the radio programs are transmitted in accordance with a multichannel transmission process, and additional regionally differing information are transmitted in transmission time windows which are not occupied by a common-wave broadcasting mode transmitted signal. The invention also concerns a transmitter and receiver for carrying out for this method.
An earth-based digital transmission method has been developed some years ago and is intended to provide for consistently high transmission quality comparable to that of digital recordings even in the event of a mobile receiver as well as a more efficient use of frequency. In the methods known in the art under the designations DAB (digital audio broadcasting) for radio and DVB (digital video broadcasting) for video transmissions, the transmission data are broadcast in a common-wave broadcasting network. In this fashion a particularly good usage of the transmission frequencies is achieved.
Known in the art from WO 88/00417 A3 is a transmission method for encoding and modulating data. Same are initially encoded with the introduction of error protection code in order to be able to recorrect transmission errors. Modulation then follows. Towards this end, a plurality of carrier frequencies are phase-modulated with the signal to be transmitted, and the carrier frequencies are scrambled in time as well as in frequency.
This transmission method has, however, the disadvantage that all information transmitted in the common-wave broadcasting network must be absolutely identical. Since, according to present plans, a common-wave broadcasting network will be broadcast across the entire country, it would then no longer be possible to transmit information in a regional manner only.
This disadvantage is obviated by the method described in DE 42 22 877 C2, wherein a method for the transmission of regionally differing information in a common-wave broadcasting network is disclosed. In accordance with this method, data are transmitted within time windows which are not occupied by a common-wave broadcasting signal via carrier frequencies also used in the other time windows. However, in contrast to common-wave broadcasting mode, these data are broadcast using frequency multiplexing via carrier frequencies which are different for each transmitter, as has been conventional up to this time in VHF transmission, so that two principally different transmission methods are utilized in a time multiplexed fashion. In this manner, it is possible to transmit the substantially larger fraction of transmission data in the common-wave broadcasting mode to make efficient use of frequency, and a small portion of the data which is only of local interest is transmitted with frequency multiplexing of the transmitter.
This has the disadvantage that the transmission capacity for local radio transmitters is insufficient, since only a relatively narrow time window (in accordance with the COFDM-protocol) is unoccupied by the common-wave broadcasting signals.
Known in the art from DE 4237692 C1 is a receiver for digital radio signals having a particularly advantageous circuit configuration. In this receiver, the received signal is split into real and imaginary signal components by switching-over an all-pass filter and is simultaneously mixed-down to an intermediate frequency. In this manner, the real and imaginary signal components are present in a time multiplexed fashion and components in the receiver are obviated which are conventionally required for parallel processing of real and imaginary components of the received signal.
Known in the art from DE 4223194 C1 is a method and a circuit configuration for the determination of the geographical location of a receiver in a common-wave broadcasting network. Towards this end, the rigidly phase-coupled transmission signal from differing transmitters is overlapped in the receiver to form beat frequencies. The subsequent localization of the receiver is facilitated by the phase difference of a plurality of beat frequencies from differing transmitters using one of the conventional hyperbolic localization methods (Decca or Loran-C).
Known in the art from DE 43 41 211 is a method and a circuit configuration for the introduction of data into a transmission signal. Herein, information which is to be transmitted only regionally is introduced in a frequency and time synchronous fashion in a DAB transmission signal of a transmitter for a common-wave broadcasting network. In this fashion it is possible to transmit regionally different additional information via transmitters in a common-wave broadcasting network whose transmission signals are normally absolutely identical.
Known in the art from DE 43 14 045 is a method for the transmission of digital, compressed audio and/or video signals, wherein the audio and/or video signals are associated with one or a plurality of radio programs. The digital data stream transmitted via the transmission channel is subdivided into a plurality of partial data streams. The partial data streams are transmitted using frequency and/or time multiplexing.